Amish Sweet and Sour Dressing for Salads

1/2 c. sugar
1/4 c. cider vinegar 
1/2 c. water
2 tbsp. cornstarch 
1 beaten egg 
1 tbsp. melted butter 

Mix sugar and vinegar together. Mix water and cornstarch together. Mix the 2 mixtures together. Add the melted butter and egg with a whisk. Cook on medium heat until the sauce thickens, stirring occasionally so it does not stick. Makes 4 servings. Serve hot or cold.